Energy storage module

Abstract

To provide a power storage module that can suppress an increase in thickness due to an overlap between an electrode coating portion of a current collector and a reinforcing member, thereby suppressing a decrease in energy density as a power storage module.SOLUTION: In a power storage module according to the present disclosure, stacked power storage cells 110, 120 include a spacer 20 that seals between the edges of the opposing current collectors 10 to form a storage space for storing an electrolyte, and a reinforcing member 22 that reinforces an uncoated portion of the current collector that is not coated with an active material layer 14. The reinforcing member has a portion that is disposed along the uncoated portion so as to straddle the peripheral portion of the active material layer and the spacer. Adjacent reinforcing members in the stacking direction have non-overlapping portions that do not overlap with each other at the peripheral portion of the active material layer.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] This disclosure relates to a power storage module.

Background Art

[0002] Patent Document 1 discloses a power storage cell including a positive electrode, a negative electrode, a separator, a spacer, and a reinforcing member. The positive electrode and the negative electrode each have an active material layer on one surface of a current collector formed of a metal foil. The positive electrode and the negative electrode are arranged such that the active material layers face each other. The separator is disposed between the positive electrode and the negative electrode and intervenes between the active material layers. The spacer is disposed between the positive electrode and the negative electrode and seals between the edges of the current collector so as to surround the active material layer to form an accommodation space for accommodating an electrolytic solution. The reinforcing member reinforces an uncoated portion of the current collector where the active material layer is not located. The current collector has the uncoated portion between the spacer and the active material layer when viewed from the direction in which the active material layers of the positive electrode and the negative electrode face each other. The reinforcing member is disposed along the uncoated portion so as to straddle the boundary between the active material layer and the uncoated portion and the boundary between the spacer and the uncoated portion when viewed from the facing direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] To suppress tearing or bending of the current collector foil due to reduced pressure or thermal shock, reinforcing members may be placed across the electrode periphery and electrode coating to increase the overall strength of the electrode body. Figure 5 shows an example where the thickness increases due to the overlap of reinforcing members when a part of the spacer is used as a reinforcing member and placed across the electrode periphery and electrode coating. As shown in Figure 5, the thickness increases in the overlapping portion 40 where the electrode coating portion (negative electrode 14) of the current collector 10 and the reinforcing member 22B (part of the spacer 20) overlap. In an energy storage module (hereinafter sometimes simply referred to as "module") in which multiple such electrode bodies are stacked, the increase in the thickness of the overlapping portion 40 becomes significant, and there is a risk that the energy density of the module will decrease.

[0005] The object of this disclosure is to provide an energy storage module that can suppress the decrease in energy density as an energy storage module by suppressing the increase in thickness due to the overlap between the electrode coating portion of the current collector and the reinforcing member. [Means for solving the problem]

[0006] The following embodiments are included as means to solve the above problems. <1> A storage module in which multiple energy storage cells are stacked, The aforementioned energy storage cell is The positive and negative electrodes are arranged with active material layers coated on the central region of one side of each of the opposing current collectors, and these layers are positioned opposite each other. A separator interposed between the positive electrode and the negative electrode's active material layer, A spacer is arranged to surround the active material layer and seal the gap between the edges of the opposing current collectors, forming a containment space in which the electrolyte is contained. The current collector includes a reinforcing member that reinforces the uncoated portion where the active material layer is not coated, When viewed from the opposing direction of the active material layers, the current collector has an uncoated portion between the spacer and the active material layer. When viewed from the aforementioned opposing direction, the reinforcing member has a portion that is positioned along the uncoated portion so as to straddle the peripheral edge of the active material layer and the spacer, When viewed from the aforementioned opposing direction, adjacent reinforcing members in the aforementioned opposing direction have non-overlapping portions that do not overlap at the peripheral edge of the active material layer. Energy storage module. <2> When viewed from the opposing direction, the reinforcing member has an uneven portion at the periphery of the active material layer, and adjacent reinforcing members in the opposing direction have non-overlapping portions at the periphery of the active material layer where the uneven portions do not overlap. <1> The energy storage module described above. <3> The non-overlapping portions of the reinforcing member are not adjacent in the opposing direction. <1> or <2> The energy storage module described above. <4> The spacer and the reinforcing member are formed as the same integrated member. <1> ~ <3> A battery storage module listed in any one of the following documents. [Effects of the Invention]

[0007] According to this disclosure, an energy storage module is provided that can suppress the amplification of thickness due to the overlap between the electrode coating portion of the current collector and the reinforcing member, thereby suppressing a decrease in energy density as an energy storage module. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view showing an example of the appearance of the energy storage module related to this disclosure. [Figure 2] This is a schematic diagram showing an example of an energy storage module constructed by alternately stacking energy storage cells having comb-shaped spacers. [Figure 3A] Figure 2 is a schematic diagram showing a cross-section of line AA'. [Figure 3B] Figure 2 is a schematic diagram showing a cross-section of line BB'. [Figure 4] This is a schematic diagram showing a structure in which reinforcing members (part of the spacers) are arranged alternately in separate layers so as not to overlap. [Figure 5]This is a schematic diagram illustrating an example of thickness amplification due to overlapping portions of reinforcing members (part of the spacer). [Modes for carrying out the invention]

[0009] The energy storage module relating to this disclosure will be described below with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals, and reference numerals and explanations are omitted as appropriate in the same drawing.

[0010] The energy storage module according to this disclosure has a configuration in which reinforcing members are stacked such that the overlapping portion where the electrode coating portion (active material layer) and the reinforcing member overlap in the stacking direction of multiple energy storage cells is discontinuous in the stacking direction. As a result, the amplification of the thickness when stacking energy storage cells is mitigated, and the decrease in energy density of the module is suppressed.

[0011] Figure 1 is a schematic perspective view showing an example of the external appearance of an energy storage module according to the present disclosure. The energy storage module 100 according to the present disclosure is a rectangular parallelepiped, as shown in Figure 1, for example. The energy storage module 100 comprises an electrode stack 102 including a stacked group of bipolar electrodes, a resin body 104 that surrounds and holds the sides of the electrode stack 102, and an electrolyte (not shown). The energy storage module 100 according to the present disclosure has a configuration in which a plurality of energy storage cells are stacked. The length and width of the energy storage module 100 are not particularly limited, but may each be greater than 1 m.

[0012] The energy storage cell comprises a positive electrode and a negative electrode formed on one side of each of two opposing current collectors, a separator, a spacer, and a reinforcing member. The reinforcing member reinforces the uncoated portion of the current collector where the active material layer of the positive or negative electrode is not coated. The reinforcing member may be a different member from the spacer, or it may be the same member as the spacer, i.e., the spacer and the reinforcing member may be integrally formed. Hereinafter, an embodiment in which the spacer and the reinforcing member are integrally formed will be described as an example of an energy storage module according to this disclosure.

[0013] FIG. 2 shows a power storage module 100 configured by alternately stacking power storage cells 110 and 120. FIG. 3A is a schematic cross-sectional view showing a cross-section along line A-A' in FIG. 2, and FIG. 3B is a schematic cross-sectional view showing a cross-section along line B-B' in FIG. 2. In FIG. 2, for convenience of explanation, illustration of the positive electrode 12, the separator 16, and the seal portion 18 is omitted.

[0014] The power storage cell 110 includes a positive electrode 12 and a negative electrode 14 formed on one surface of the opposing current collectors 10, a separator 16, a spacer 20A, and a reinforcing member 22A. Further, the power storage cell 120 includes a positive electrode 12 and a negative electrode 14 formed on one surface of each of the opposing current collectors 10, a separator 16, a spacer 20B, and a reinforcing member 22B.

[0015] The positive electrode 12 and the negative electrode 14 are formed such that the active material layers coated on the central regions of one surface of each of the opposing current collectors 10 face each other. The separator 16 is interposed between the active material layers 12 and 14 of the positive electrode 12 and the negative electrode 14 (between the positive electrode 12 and the negative electrode 14). The spacers 20A and 20B are arranged so as to surround the active material layers 12 and 14, and seal between the edges of the opposing current collectors 10 to form an accommodation space T in which an electrolytic solution is accommodated. When viewed from the direction in which the active material layers 12 and 14 face each other (the same as the stacking direction of the power storage cells 110 and 120), there are uncoated portions between the current collectors 10 and the spacers 20A and 20B and the active material layers 12 and 14. The reinforcing members 22A and 22B reinforce the uncoated portions of the current collectors 10 where the active material layers 12 and 14 are not coated. When viewed from the direction in which the active material layers 12 and 14 face each other, the reinforcing members 22A and 22B have portions arranged along the uncoated portions so as to straddle the peripheral edges of the active material layers 12 and 14 and the spacers 20A and 20B.

[0016] In the present embodiment, the spacer 20A and the reinforcing member 22A, and the spacer 20B and the reinforcing member 22B are formed as the same integrated members. As shown in Figure 2, the spacers 20A and 20B in each energy storage cell 110 and 120 have an uneven shape (sometimes referred to as a "comb shape") when viewed from the opposite direction (the same as the stacking direction). With spacers 20A and 20B having such a comb shape, the recessed parts function as spacers 20A and 20B for forming the electrolyte storage space T, and the convex parts function as reinforcing members 22A and 22B that reinforce the uncoated portions where the active material layer 14 is not coated.

[0017] In this embodiment, comb-shaped spacers 20A and 20B are arranged in the space on the positive electrode 12 side, and the ends of the reinforcing members 22A and 22B overlap the peripheral edge on the negative electrode 14 side. Because the energy storage cells 110 and 120 are stacked alternately in this way, the overlap between the reinforcing members (comb-shaped portion) 22 and the negative electrode 14 does not accumulate in the stacking direction, which reduces the bulging inside the module and reduces the unevenness of the module. The total thickness of the module does not increase, and the decrease in energy density is suppressed. In addition, the space is necessary for gas generation due to charging and discharging, and by making the spacers 20A and 20B comb-shaped, it is possible to secure a wide space (accommodation space) Y, which is an advantage.

[0018] Each of the energy storage cells 110 and 120 is configured such that when stacked alternately, the position of the convex portion of the spacer in one energy storage cell corresponds to the position of the concave portion of the spacer in the other energy storage cell. Therefore, by stacking the energy storage cells 110 and 120 alternately to form an energy storage module, the convex portions of the spacers, which function as reinforcing members, of adjacent energy storage cells 110 and 120 in the stacking direction do not continuously overlap in the stacking direction. When the energy storage cells 110 and 120 are stacked alternately, the reinforcing members 22A and 22B adjacent to each other in the opposing direction (stacking direction) become non-overlapping portions where the protrusions and recesses do not overlap at the periphery of the active material layers 12 and 14. Therefore, when stacking energy storage cells, the amplification of thickness due to the overlap of reinforcing members in the stacking direction is mitigated, and the decrease in energy density as a module is suppressed.

[0019] Although the recesses of each reinforcing member 22A and 22B are non-overlapping portions, even if the recesses of each reinforcing member 22A and 22B are adjacent in opposing directions when the energy storage cells 110 and 120 are stacked, the effect of suppressing the accumulation of overlap between the reinforcing member 22 and the negative electrode 14 cannot be obtained. For this reason, it is preferable that the non-overlapping portions (recesses) of the reinforcing members 22A and 22B are not adjacent in opposing directions.

[0020] The method for manufacturing the energy storage module 100 according to this disclosure is not particularly limited. The energy storage module according to this disclosure can be manufactured by sequentially stacking electrode bodies and spacers. An example of a method for manufacturing the energy storage module according to this disclosure will be described below. Figure 4 shows an example of a method for manufacturing the energy storage module according to this disclosure.

[0021] First, as shown in Figure 4(A), electrode bodies with sealing portions 18 welded to the outer circumference of the current collector 10 are stacked. Next, as shown in Figure 4(B), separators 16 are stacked on the negative electrode 14. Then, as shown in Figure 4(C), comb-shaped spacers 20 are stacked. The comb-shaped spacers 20 are arranged alternately in layers so that the comb-shaped portions (reinforcement members) of adjacent cells do not overlap in the stacking direction. Next, as shown in Figure 4(D), electrode bodies with sealing portions 18 welded to the outer circumference are stacked. By repeating the stacking process in this manner, an energy storage module is obtained in which multiple energy storage cells are stacked, with the accumulation of overlap between the reinforcing member 22 and the negative electrode 14 being suppressed.

[0022] The following describes in detail the constituent materials of the energy storage module related to this disclosure, but the constituent materials of the energy storage module related to this disclosure are not limited to the following description.

[0023] (Electrode stack) The electrode stack 102 is a rectangular parallelepiped. The electrode stack 102 includes a plurality of bipolar electrodes stacked via separators 16. As shown in Figures 3A and 3B, the electrode stack 102 has a plurality of bipolar electrodes, a plurality of separators 16, a positive terminal electrode (not shown), and a negative terminal electrode (not shown). The plurality of bipolar electrodes and the plurality of separators 16 are stacked alternately along the axial direction. The positive terminal electrode is stacked via separators 16 on the bipolar electrode that is located furthest in one direction of the stacking among the plurality of bipolar electrodes. The negative terminal electrode is stacked via separators 16 on the bipolar electrode that is located furthest in the other direction of the stacking among the plurality of bipolar electrodes.

[0024] The bipolar electrode includes a current collector 10, a positive electrode 12, and a negative electrode 14. The peripheral edge of the current collector 10 is welded to a resin body 104 (seal portion 18). The positive electrode 12 is formed on one side of the current collector 10. The negative electrode 14 is formed on the other side of the current collector 10. The bipolar electrode may have a known configuration.

[0025] The current collector 10 supplies current to the positive electrode 12 and the negative electrode 14 during the discharge or charging of the energy storage module 100. Examples of materials for the current collector 10 include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. A coating layer may be formed on the surface of the current collector 10 by known methods (e.g., plating, spray coating, etc.). The thickness of the current collector 10 may be 1 μm to 100 μm.

[0026] The positive electrode 12 includes a positive electrode active material (e.g., lithium composite metal oxide having a layered rock salt structure, metal oxide with a spinel structure, polyanionic compound, etc.) capable of intercalating and releasing charge carriers. The positive electrode 12 may further include, if necessary, a conductive additive (e.g., carbon nanofiber, etc.) to enhance electronic conductivity, a binder (e.g., polyvinylidene fluoride, etc.), an electrolyte support salt (lithium salt) to enhance ionic conductivity, a polymer electrolyte, and additives (e.g., trifluoropropylene carbonate, filler as a reinforcing material, etc.). The thickness of the positive electrode 12 may be 2 μm to 500 μm.

[0027] The negative electrode 14 contains a negative electrode active material (e.g., carbon (e.g., natural graphite, artificial graphite), a compound alloyable with lithium (e.g., silicon, tin, etc.)) capable of intercalating and releasing charge carriers. The negative electrode 14 may further contain, if necessary, a conductive additive to enhance electronic conductivity (e.g., acetylene black), a binder (e.g., polyvinylidene fluoride, etc.), an electrolyte support salt (lithium salt) to enhance ionic conductivity, a polymer electrolyte, and additives (e.g., trifluoropropylene carbonate, fillers as reinforcing materials, etc.). The thickness of the negative electrode 14 may be 2 μm to 500 μm. The thickness of the negative electrode 14 may be the same as or different from the thickness of the positive electrode 12. In this embodiment, as shown in Figures 3A and 3B, the length of the negative electrode 14 is longer than the length of the positive electrode 12.

[0028] (Separator) The separator 16 maintains the distance between the positive electrode 12 and the negative electrode 14 to prevent contact short circuits and allows charge carriers such as lithium ions to pass through. The periphery of the separator 16 is welded to the resin body 104 (seal portion 18). The separator 16 is held in place by the resin body 104. Examples of the separator 16 include a porous resin sheet or a nonwoven fabric. Examples of materials for the porous resin sheet include polyolefins (polypropylene, polyethylene, etc.). Examples of materials for the nonwoven fabric include polypropylene, polyethylene terephthalate, methylcellulose, etc. The separator 16 may also have a known configuration.

[0029] (Resin body) The resin body 104 forms a housing space T between adjacent bipolar electrodes in the stacking direction. The positive electrode 12, the negative electrode 14, and the separator 16 are housed in the housing space T, contained in an electrolyte. In this embodiment, the resin body 104 prevents the electrolyte housed in the housing space T from leaking to the outside. The resin body 104 can prevent moisture from entering the housing space T from outside the energy storage module 100. The resin body 104 prevents internal gas generated from the positive electrode 12 or the negative electrode 14 due to charging and discharging from leaking to the outside of the energy storage module 100.

[0030] The resin body 104 is a rectangular tubular object with a rectangular cross-section. The resin body 104 includes a sealing portion 18 that holds the periphery of the current collector 10 and the separator 16, as well as a spacer 20 and a reinforcing member 22 Includes. The sealing portion 18 is positioned along the stacking direction for each of the current collector 10 and separator 16. The sealing portion 18 is a rectangular tubular object with a rectangular cross-section. The sealing portion 18 is welded to the periphery of the current collector 10. In the stacking direction, adjacent sealing portions 18 are welded to each other. Therefore, the periphery of the current collector 10 and the periphery of the separator 16 are held in a state of being embedded in the resin body 104. Examples of materials for the resin body 104 (seal portion 18, spacer 20, reinforcing member 22) include polyethylene, polystyrene, and acrylonitrile-butadiene-styrene copolymer synthetic resins (ABS resin, modified polypropylene, acrylonitrile styrene resin, etc.).

[0031] (electrolyte) The electrolyte is contained in a containment space T. The electrolyte may contain a non-aqueous solvent and a lithium salt. Examples of lithium salts include LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2. Examples of non-aqueous solvents include cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers. The non-aqueous electrolyte may contain additives (e.g., lithium bis(oxalato)borate). [Explanation of Symbols]

[0032] 10 Current collector, 12,14 Active material layer, 12 Negative electrode, 12 Positive electrode, 14 Active material layer, 14 Negative electrode, 16 Separator, 18 Seal part, 20 Spacer, 22 Reinforcement member, 40 Overlap part, 100 Energy storage module, 102 Electrode laminate, 104 Resin body, 110,120 Energy storage cell

Claims

1. A storage module in which multiple energy storage cells are stacked, The aforementioned energy storage cell is The positive and negative electrodes are arranged with active material layers coated on the central region of one side of each of the opposing current collectors, and these layers are positioned opposite each other. A separator interposed between the positive electrode and the negative electrode's active material layer, A spacer is arranged to surround the active material layer and seal the gap between the edges of the opposing current collectors, forming a containment space in which the electrolyte is contained. The current collector includes a reinforcing member that reinforces the uncoated portion where the active material layer is not coated, When viewed from the opposing direction of the active material layers, the current collector has an uncoated portion between the spacer and the active material layer. When viewed from the aforementioned opposing direction, the reinforcing member is intermittently arranged along the uncoated portion so as to straddle the peripheral edge of the active material layer and the spacer. When viewed from the aforementioned opposing direction, adjacent reinforcing members in the aforementioned opposing direction have non-overlapping portions that do not overlap at the peripheral edge of the active material layer. Energy storage module.

2. The energy storage module according to claim 1, wherein, when viewed from the opposing direction, the reinforcing member has an uneven portion at the periphery of the active material layer, and adjacent reinforcing members in the opposing direction have non-overlapping portions at the periphery of the active material layer where the uneven portions do not overlap.

3. The non-overlapping portions of the reinforcing member are not adjacent in the opposing direction, as described in claim 1 or claim 2 of the energy storage module.

4. The energy storage module according to claim 1 or claim 2, wherein the spacer and the reinforcing member are formed as the same integrated member.

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